Thin film transistors have been used as drive elements or switching elements in active matrix display apparatuses, such as liquid crystal display apparatuses that include liquid crystals or organic light-emitting diode (OLED) display apparatuses that include organic electroluminescence (EL).
Moreover, such a display apparatus includes a thin film transistor substrate which has, on one and the same substrate, both a display element that includes pixels arranged in a matrix and a drive circuit that drives the display element. Thin film transistors are used in the drive circuit and the pixels of the display element in the thin film transistor substrate. Here, the required characteristics are different between the thin film transistor used in the drive circuit and the thin film transistor used for driving a light-emitting element in the pixel. To be more specific, the thin film transistor used in the drive circuit is required to have a high carrier mobility in a channel to enable high speed drive of the display element. On the other hand, the thin film transistor used for driving the light-emitting element in the pixel is required to have characteristics that enables current supply corresponding to the light-emitting element. In view of this, a thin film transistor substrate has been proposed which is provided with: a thin film transistor that has a channel formed from low-temperature polysilicon and is used in a drive circuit; and a thin film transistor that has a channel formed from amorphous silicon and is used in a pixel (Non Patent Literature [NPL] 1).